Caption: Animation showing the pressure-temperature law in an ideal gas. The dials at right show the pressure (P), temperature (T) and volume (V) of the gas. The law states that, at a constant volume, a decrease in the temperature of a gas causes a proportional decrease in its pressure. When the coolers are applied to the box, the particles of gas (grey) cool down (turning blue), and travel much more slowly. Their slower motion causes less frequent collisions with the sides of the container, which is seen as decreased pressure. The law is attributed to Jospeh Louis Gay-Lussac (1778-1850), but the basic principle had been established some 100 years beforehand by Guillame Amontons (1663-1705). This animation is part of a series on the ideal gas laws. See K003 3525-3530 for the complete set.